Device and method for folding foldable blanks

ABSTRACT

A device for folding foldable blanks device includes a conveyor belt for conveying the blanks and a folding cylinder for receiving a first region of a blank from the conveyor belt, wherein the conveyor belt is provided with a plurality of suction openings which are arranged such that, by means of a vacuum unit assigned thereto, the suction openings hold a second region of the foldable unfashioned piece on the conveyor belt at least during folding.

The invention relates to a device for folding foldable blanks, in particular envelopes, comprising a conveyor belt for conveying the blanks and a folding cylinder for receiving a first region of a blank from the conveyor belt. The invention further relates to a method for folding a foldable blank using the method steps.

In particular in the production of envelopes, blanks are now folded in a fully automated manner by corresponding systems. In the process, high demands are placed on the devices, since large-scale production is required on one hand, and a clean fold at a precise position is desired on the other.

WO 99/47348, for example, discloses a system of this type, which can fold paper blanks transverse to the conveying direction at high speed. For this purpose, a roller system is provided, which comprises a conveying roller and a folding roller for receiving the region, which is to be folded, of the paper blank. In the process, the folding roller receives the front edge of the paper blank which is conveyed along the conveying roller. The remaining region of the paper blank is then guided below the front edge as a result of the rotary movement of the conveying roller, whereby a fold is formed transverse to the conveying direction. The paper blank folded thus can then be processed further in subsequent method steps.

As the folding processes became ever more automated, there was a demand for the item to be packaged, i.e. the content, to be sent, of the envelope, to have already been fed in or to be fed in during folding of the envelopes. Therefore, once the folding process is complete, the envelope has not just been folded and has to be filled in a downstream filling process and then closed, but the envelope has already been completely filled following the folding process. Subsequent method steps for filling the envelope can thus be avoided.

U.S. Pat. No. 3,593,486 describes a system of this type, in which the envelope is filled as early as during folding. In this case too, the system again comprises a roller system having a conveying roller for the envelope. The front edge of the paper blank is also raised again in this case, although this time only by means of an overpressure system in the conveying roller. During folding, the item to be sent is now inserted by being slid onto the fold obliquely to the conveying direction. An adjacent roller then folds the raised bottom flap of the paper blank onto the item and the front wall of the envelope.

A particular drawback of this system is the location at which the item to be packaged is fed in. Since the item to be packaged is fed in during the folding process, a folding cylinder has to be omitted, since the available space, which is only limited, in the system is required for the feed unit. This also means that only one feed unit is possible, and therefore the separate feed of for example correspondence and additional informational flyers is not possible. Targeted feeding of the item onto or against the fold also leads to the fold being loaded during the folding process, and this can lead to damage or displacement of the fold (if the load from the material fed in is uneven).

Therefore, the problem addressed by the invention is that of providing a device and a method in which blanks, in particular for envelopes, both having and not having an item to be packaged can be cleanly and precisely folded in large-scale production.

In terms of the device, this problem is solved according to the invention by the conveyor belt being provided with a plurality of suction openings which are arranged such that, by means of a vacuum unit assigned thereto, they hold a second region of the foldable unfashioned piece on the conveyor belt at least during folding. In terms of the method, this problem is solved according to the invention by the following method steps:

-   -   conveying the blank in a conveying direction x by means of a         conveyor belt,     -   holding a second region of the blank on the conveyor belt by         means of a suction device,     -   receiving a first region of the blank, which is in front of the         second region in the conveying direction x, by means of a         folding cylinder,     -   folding the blank by the second region being guided further in         the conveying direction x and below the first region,     -   placing the first region on the second region by the folding         cylinder releasing the first region.

Advantageous embodiments form the subject matter of the dependent claims.

The invention is based on the consideration that the item to be packaged should preferably be fed in before the blank is folded, so that the upstream feed unit can be designed and formed independently of the folding device, so that even a plurality of additional items can be packaged together in an extremely simple manner, and also so that the feed unit does not interrupt, impair or otherwise, for example owing to the required space, affect the folding process. The item to be packaged and the unfashioned envelope piece or paper blank can be fed in with precise positioning in particular when the blank does not perform a circular movement, but rather is guided horizontally. A paper blank can be conveyed horizontally in such a manner by means of a correspondingly arranged conveyor belt.

In order to prevent the contents from slipping on the paper blank during the folding process, but in particular to also prevent the paper blank from slipping on the conveyor belt, and to thus allow for a particularly clean and precise fold transverse to the conveying direction, the conveyor belt is provided with a plurality of suction openings which securely hold the paper blank on the conveyor belt by means of a vacuum system. The region to be folded (generally the bottom flap in the case of envelopes) can now be raised by the folding cylinder independently of the item to be packaged, and folded over along the fold.

In order to hold the blank particularly strongly on the conveyor belt, in an advantageous embodiment the suction openings are arranged in rows which extend parallel to the fold and thus transverse to the conveying direction. In this case, in a particularly advantageous embodiment the row of suction openings that is directly adjacent to the fold comprises the highest number of suction holes. The blank is thus held particularly strongly on the conveyor belt at the precise point where most of the forces act on the second region of the blank during folding, which forces could cause the blank to slip.

However, the trailing regions of the blank, i.e. the regions that follow when viewed in the conveying direction of the fold, are not subjected to such great forces, but nevertheless have to be held firmly and in a slip-proof and rotation-proof manner. For energy saving reasons, in an advantageous embodiment the number of suction openings therefore reduces with each row. Therefore, the number of suction openings becomes smaller or at most remains constant with each additional row further away from the fold. The rear regions are thus also adequately held without the need for an unnecessarily large vacuum system.

To assist the folding process and for a particularly clean and precise fold, in a preferred embodiment the device comprises a folding plate which is arranged downstream of the folding cylinder in the folding process. Owing to its arrangement, this folding plate favours uniform placement of the raised first region on the second region of the blank or on the item to be packaged that is resting on the second region of the blank.

For uniform pressing and thus flat resting of the raised first region, in an advantageous embodiment a plurality of flattening rollers are provided, which can be arranged upstream and/or downstream of the folding plate depending on the configuration. When corresponding adhesive strips are attached to the first or second region of the blank, said flattening rolls also promote the bonding of the folded blank.

The advantages obtained with the invention are in particular that, by using a conveyor belt having suction openings not only to supply the blank but also when the blank is folded, folding can also take place even if there is already an item to be packaged on the blanks. The item to be packaged thus barely impairs and affects the folding. The particular arrangement of the hole pattern of the suction openings also achieves a particularly secure hold of the blank on the conveyor belt, while the vacuum unit is used in an energy-efficient manner at the same time.

An embodiment of the invention will be described in greater detail with reference to the drawings, in which:

FIG. 1 shows a device for folding a foldable blank;

FIG. 2 shows a schematic detail of FIG. 1;

FIG. 3 is a schematic view of the method steps;

FIG. 4 shows a conveyor belt having suction openings.

Like parts are provided with the same reference numerals in all the drawings.

An embodiment of a device 1 for folding foldable blanks (envelopes in the embodiment) is shown in FIG. 1 and a schematic detail of the device is shown in FIG. 2. In this case, the device 1 comprises a conveyor belt 2, on which unfashioned envelope pieces provided as blanks 4 to be folded are located and are conveyed in the conveying direction x. In this case, the conveyor belt 2 conveys the blanks 4 prior to folding, during folding and also following folding, and then transfers said blanks to an additional device for further processing of the blank 4, for example for folding its side flaps. To convey the blanks 4 in a uniform and controlled manner, the device 1 comprises a driving roller 6 and a plurality of guide rollers 8, which are arranged such that the conveyor belt 2 is sufficiently taut and thus flat on one hand, and such that the blanks 4 can be conveyed horizontally on the other hand.

A vacuum unit 10 is provided below the horizontal portion of the conveyor belt 2 and thus below the portion of the conveyor belt 2 along which the blanks or unfashioned envelope pieces are conveyed. Said vacuum unit 10 sucks the blanks 4 by means of a plurality of suction openings 12 on the conveyor belt 2, so that said blanks are held in a slip-proof manner during conveyance. In this context, just one vacuum chamber 10 is provided in the present embodiment, which chamber extends over the short portion in which the blank 4 has to be held during the folding process. Depending on the application, however, it is also possible to form the vacuum unit 10 over the entire conveying path, so that the blank 4 is constantly held in a slip-proof manner.

By contrast, a folding cylinder 14 or a vibrator roller is arranged above the horizontal portion of the conveyor belt 2 and can receive and raise, from the conveyor belt 2, each unfashioned envelope piece or blank 4 or part 16 of the blank 4. For this purpose, the folding cylinder 14 also comprises a vacuum unit and a plurality of suction openings 18 which are arranged on the circumferential surface of the folding cylinder 14 and can suck and thus raise the side, facing away from the conveyor belt 2, of the first region 16 of the blanks 4. A folding plate 20, which promotes the folding process, is also arranged above the horizontal portion of the conveyor belt 2 downstream of the folding cylinder 14 in the folding process. Downstream of the folding plate 20 in the folding process, a flattening roller 22 is also arranged, which promotes clean folding. In an alternative configuration or within the scope of an additional configuration, however, said flattening roller 22 can also be arranged directly upstream of the folding plate 20 by means of a second flattening roller.

The folding process is shown in a schematic view in FIG. 3 in 5 method steps selected by way of example.

-   -   (1) In this case, the blank 4 rests on the conveyor belt 2 and         is held in a slip-proof manner by suction openings 12 in the         conveyor belt 2, to which openings a vacuum is applied. In this         context, the suction openings 12 act only on a second region 24,         typically the front wall and optionally the side flaps, and not         on a first region 16, typically the bottom flap of the blank 4,         since said bottom flap is raised during the subsequent folding         process.     -   (2) Once the front edge of the bottom flap 16 passes the folding         cylinder 14, said bottom flap is raised by means of suction         holes 18, which are arranged in the circumferential surface of         the folding cylinder 14 and to which a vacuum is likewise         applied, and guided along the folding cylinder 14         (anti-clockwise in the point of view shown). In this method         step, the blank 4 is thus held by two independent vacuum         systems, the direction of movement of which is different. The         front wall 24 of the blank 4 is also held on the conveyor belt 2         and moved in the conveying direction x, while the bottom flap 16         is raised and guided along the folding cylinder 14 on a circular         path.     -   (3) As soon as the whole of the bottom flap 16, which is to be         folded, has been raised, the vacuum in the folding cylinder is         released and the bottom flap 16 is no longer held by the folding         cylinder 14. The front wall of the blank, however, is still held         on the conveyor belt 2 and moved in the conveying direction x.         This continuation of the movement of the front wall 24 now leads         to the bottom flap 16 being folded along the bottom fold 26. In         this case, a folding plate 20, which is arranged downstream of         the folding cylinder 14 in the folding process, promotes the         placement of the bottom flap 16 onto the front wall 24. In an         alternative configuration of the folding cylinder 14, said         cylinder can actively promote the folding process when a vacuum         is applied and by means of a clockwise rotation.     -   (4) A flattening roller 22, which can be arranged downstream of         the folding plate 20 in the folding process, provides for clean         folding and tight resting of the bottom flap 16 on the front         wall 24.     -   (5) As soon as the blank 4 has passed the folding cylinder 14,         the folding plate 20 and the flattening roller 22, the folding         of the bottom flap 16 is complete. In this case, the folded         blank 4 is still on the conveyor belt 2 and can be held in a         slip-proof manner by means of a plurality of suction openings 12         to which a vacuum is applied. The folded blank 4 can now be         transferred to a downstream device for further processing, for         example further folding of or printing on the bottom flap 16.

It is also possible for an adhesive or bonding strip to be attached to the blank 4 in a preceding step by means of a bonding unit, so that folding bonds the front wall 24 or side flaps to the bottom flap 16. As already mentioned, it is likewise provided that a plurality of additional blanks, for example an item 28 to be packaged that is covered or packaged by the folding of the bottom flap 16, is optionally located on the front wall 24 of the blank 4. In this process, these items 28 to be packaged or enclosed are held on the region of the front wall 24 of the blank 4 by means of a top belt 30, which runs at the same speed as the conveyor belt 2 formed as a suction belt. For this reason, in the present configuration the folding cylinder 14 also comprises two individual, narrow folding rollers which are arranged at a distance from one another on a common rotary shaft 32. The top belt 30 projects into said gap between the two folding rollers, so that the item 28 to be packaged can be held on the blank 4 until the folding process.

FIG. 4 shows one embodiment of a conveyor belt 2 having an exemplary hole pattern of suction openings 12. In this case, two unfashioned envelope pieces 4 are shown on the suction belt 2, which pieces are held on the conveyor belt 2 in a slide-proof manner by means of the suction openings 12 and are moved in the conveying direction x together with and/or by the conveyor belt 2. In this context, the suction openings 12 on the conveyor belt 2 are not uniformly distributed over the conveyor belt 2, but rather are arranged in specific places where particularly good adhesion of the unfashioned envelope piece 4 is desired during folding.

It has been found in this context that good adhesion of the blank 4, which is to be folded, to the conveyor belt 2 is desirable directly along the fold 26 and on the side thereof with the front wall 24. For this reason, in the present case of the transverse folding of the bottom flap 16 of the unfashioned envelope piece, a particularly high number of suction openings 12 are provided in a portion b₁ of the front wall 24 that is adjacent to the fold 26, which openings extend substantially over the entire width of the conveyor belt 2. In the present case, the portions b₁, b₂ . . . b_(n) are selected such that each row of suction openings 12 is in its own portion b₁, b₂ . . . b_(n). However, in the subsequent portions b₂, b₃ . . . b_(n) of the front wall 24, which are further away from the fold 26, a lower density of suction openings 12 is provided. In the present embodiment, at first this density of suction openings 12 decreases constantly the further away the region is from the fold 26 until said density then remains constant, before no more suction holes 12 are provided. In this case, the number of portions b₁, b₂ . . . b_(n) in which suction openings 12 are provided is adapted to the size of the blanks 4 to be folded, and preferably extends at least over the entire length of the front wall 24. The number of portions b₁, b₂ . . . b_(n) and also the number of suction openings 12 or the width over which the suction holes 12 extend transverse to the conveying direction x in the region of the fold 6 are thus adapted to the largest format to be folded of a blank 4. As a result, it is possible to process any given formats of blanks 4 without changing the conveyor belt 2 or shutting down the device 1.

The result of this specific hole pattern and the particular distribution of the suction openings 12 is that the bottom flap 16 of the unfashioned envelope piece 4 can be raised in a particularly simple manner, since no suction openings 12 are provided in this region. The folding itself can, however, be carried out particularly precisely, since the front wall 24 of the unfashioned envelope piece 4 is held on the conveyor belt 2, in the region of the fold 26, by means of a plurality of suction openings 12 along the fold 26. Since the remaining region of the front wall 24 is also intended to be held on the conveyor belt 2 in a slide-proof and in particular also a rotation-proof manner, although, as has been shown, it is not necessary to apply such high pressures here as are desired along the fold 26, there is no need to distribute the suction openings 12 along the entire width of the suction belt 2. This is also desirable in particular for energy saving reasons. The extension of the resultant triangular or T-shape of the hole pattern of the suction openings 12 both along the conveyor belt and transverse thereto prevents rotation of the blank 4, which is to be folded, in a particularly effective manner.

LIST OF REFERENCE NUMERALS

-   1. Folding device -   2. Conveyor belt -   4. Blank -   6. Driving roller -   8. Deflection roller -   10. Vacuum unit -   12. Suction openings -   14. Folding cylinder -   16. First region of the blank -   18. Suction holes -   20. Folding plate -   22. Flattening roller -   24. Second region of the blank -   26. Fold -   28. Item -   30. Top belt -   32. Rotary shaft -   x Conveying direction -   b₁, b₂ . . . b_(n) Portions of the blank 

1-7. (canceled)
 8. A device for folding foldable blanks, comprising: a conveyor belt for conveying the blanks; and a folding cylinder for receiving a first region of one of the a blanks from the conveyor belt said conveyor belt being provided with a plurality of suction openings said suction openings being arranged so that, by means of a vacuum unit assigned to the suction openings, the suction openings hold a second region of the blank on the conveyor belt at least during folding.
 9. The device of claim 8, wherein the suction openings are arranged in a plurality of rows which extend transverse to a conveying direction of the blank.
 10. The device of claim 9, wherein one of the rows of suction openings is directly adjacent to an intended fold of the blank resting on the suction openings and has a larger number of suction openings than any of the remaining rows of suction openings.
 11. The device of claim 9, wherein the number of suction openings in each of the rows either decreases in steps or remains constant, starting from the intended fold of the blank, and counter to the conveying direction.
 12. The device of claim 8, further comprising a folding plate arranged downstream of the folding cylinder in the conveying direction.
 13. The device of claim 8, further comprising a plurality of flattening rollers.
 14. A method for folding a foldable blank, comprising: conveying the blank in a conveying direction by means of a conveyor belt; holding a first region of the blank on the conveyor belt by means of a suction device; receiving a second region of the blank, situated in front of the first region in the conveying direction, by means of a folding cylinder; folding the blank by guiding the first region further in the conveying direction and below the second region; and placing the second region on the first region by causing the folding cylinder to release the second region. 